The
river sharks are six (two to be formally described) rare species of
sharkSharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago, before the time of the dinosaurs....
in the
genusIn biology, a genus is a taxonomic unit used in the classification of living and fossil organisms. The term comes from Latin genus "descent, family, type, gender" , cognate with – genos, "race, stock, kin" ..In addition, genus is a taxonomic rank in the hierarchy In biology, a genus (plural:...
Glyphis, although, due to their secretive habits, other species could easily remain undiscovered. The river sharks are members of the family Carcharhinidae, and thus share the basic characteristics of the group. The
bull sharkThe bull shark, Carcharhinus leucas, also known as the whaler shark, Zambezi shark or unofficially known as Zambi in Africa and Nicaragua shark in Nicaragua, is a shark common worldwide in warm, shallow waters along coasts and in rivers. The bull shark is well known for its unpredictable, often...
is sometimes called both the river shark and the Ganges shark; it should not be confused with the true river sharks of
Glyphis.
In general, all river sharks feature the following field characteristics:
- a short, broadly rounded snout (its length less than the mouth width);
- small, widely spaced nostrils;
- small, dark eyes;
- broad, serrated upper teeth;
- very short labial furrows (lip grooves), restricted to the jaw corners;
- a broad dorsal fin
A dorsal fin is a fin located on the backs of some fish, whales, dolphins, and porpoises, as well as the ichthyosaurs. Depending on the species, an animal can have up to three of them. Its main purpose is to stabilize the animal against rolling and assist in sudden turns...
with the mid-base closer to the base of the pectoral fins than those of the pelvic fins; and
- an anal fin with a deeply excised posterior margin.
River sharks are very similar in overall morphology to
requiem sharkRequiem sharks refers to all members of the family Carcharhinidae: this includes migratory, live-bearing sharks of warm seas such as the tiger shark, the blue shark, the bull shark, and the milk shark. The name comes from the French word for shark, "requin". Family members have the usual...
s of the genus
CarcharhinusCarcharhinus is the type genus of the requiem shark family, Carcharhinidae.- Species :* Blacknose shark, Carcharhinus acronotus
* Silvertip shark, Carcharhinus albimarginatus
...
, but can be distinguished from them by the following characteristics:
- cusps of lower teeth protrude prominently when mouth is closed;
- the second dorsal fin
A dorsal fin is a fin located on the backs of some fish, whales, dolphins, and porpoises, as well as the ichthyosaurs. Depending on the species, an animal can have up to three of them. Its main purpose is to stabilize the animal against rolling and assist in sudden turns...
is 1/2 to 3/5 the height of the first dorsal finA dorsal fin is a fin located on the backs of some fish, whales, dolphins, and porpoises, as well as the ichthyosaurs. Depending on the species, an animal can have up to three of them. Its main purpose is to stabilize the animal against rolling and assist in sudden turns...
;
- the origin of the second dorsal fin is slightly anterior to the origin of the anal fin;
- precaudal pit is longitudinal rather than crescent-shaped.
- Ganges shark
The Ganges shark, Glyphis gangeticus, is a rare species of fresh water shark that dwells in the Ganges River. It should not be confused with the Bull shark, which also inhabits the Ganges River and is sometimes referred to as the Ganges shark....
, Glyphis gangeticus (MüllerJohannes Peter Müller , was a German physiologist, comparative anatomist, and ichthyologist not only known for his discoveries but also for his ability to synthesize knowledge.-Life:Müller was born in Koblenz....
& HenleFriedrich Gustav Jakob Henle was a German physician, pathologist and anatomist. He is credited with the discovery of the loop of Henle in the kidney. His essay "On Miasma and Contagia" was an early argument for the germ theory of disease...
, 1839)
- New Guinea river shark
The New Guinea river shark, Glyphis garricki, formerly Glyphis sp. C, is a recently described shark of the family Carcharhinidae. Its length is thought to be up to 2 m.Reproduction is viviparous, with three to eight pups per litter....
, Glyphis garricki CompagnoLeonard J. V. Compagno is an international authority on shark taxonomy and the author of many scientific papers and books on the subject, best known of which is his 1984 catalogue of shark species produced for the Food and Agriculture Organization of the United Nations.-Career:*Ph.D, Stanford...
, White, & Last, 2008
- Speartooth shark
The speartooth shark, Glyphis glyphis, is a shark of the family Carcharhinidae, found in the tropical waters of the western Pacific Ocean between latitudes 5° N and 21° S. This little-known species has an uncertain occurrence in Malaysia, Papua New Guinea, and Queensland, Australia. The...
, Glyphis glyphis (MüllerJohannes Peter Müller , was a German physiologist, comparative anatomist, and ichthyologist not only known for his discoveries but also for his ability to synthesize knowledge.-Life:Müller was born in Koblenz....
& HenleFriedrich Gustav Jakob Henle was a German physician, pathologist and anatomist. He is credited with the discovery of the loop of Henle in the kidney. His essay "On Miasma and Contagia" was an early argument for the germ theory of disease...
, 1839)
- Irrawaddy River shark
The Irrawaddy river shark, Glyphis siamensis, is a shark of the family Carcharhinidae, found in the tropical waters of the eastern Indian Ocean off the coast of Burma.The only known specimen is from the Ayeyarwady River, near Yangon...
, Glyphis siamensis (SteindachnerFranz Steindachner was an Austrian zoologist.Being interested in natural history, Steindachner took up the study of fossil fishes on the recommendation of his friend Eduard Suess...
, 1896)
- Bizant river shark
The Bizant river shark, Glyphis sp. A, is a scientifically undescribed shark of the family Carcharhinidae, found in the tropical waters about Australia. Its length is thought to be up to 2 m, possibly 3.Reproduction is presumed to be viviparous....
, Glyphis sp.
Discussion
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The
river sharks are six (two to be formally described) rare species of
sharkSharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago, before the time of the dinosaurs....
in the
genusIn biology, a genus is a taxonomic unit used in the classification of living and fossil organisms. The term comes from Latin genus "descent, family, type, gender" , cognate with – genos, "race, stock, kin" ..In addition, genus is a taxonomic rank in the hierarchy In biology, a genus (plural:...
Glyphis, although, due to their secretive habits, other species could easily remain undiscovered. The river sharks are members of the family Carcharhinidae, and thus share the basic characteristics of the group. The
bull sharkThe bull shark, Carcharhinus leucas, also known as the whaler shark, Zambezi shark or unofficially known as Zambi in Africa and Nicaragua shark in Nicaragua, is a shark common worldwide in warm, shallow waters along coasts and in rivers. The bull shark is well known for its unpredictable, often...
is sometimes called both the river shark and the Ganges shark; it should not be confused with the true river sharks of
Glyphis.
Characteristics
In general, all river sharks feature the following field characteristics:
- a short, broadly rounded snout (its length less than the mouth width);
- small, widely spaced nostrils;
- small, dark eyes;
- broad, serrated upper teeth;
- very short labial furrows (lip grooves), restricted to the jaw corners;
- a broad dorsal fin
A dorsal fin is a fin located on the backs of some fish, whales, dolphins, and porpoises, as well as the ichthyosaurs. Depending on the species, an animal can have up to three of them. Its main purpose is to stabilize the animal against rolling and assist in sudden turns...
with the mid-base closer to the base of the pectoral fins than those of the pelvic fins; and
- an anal fin with a deeply excised posterior margin.
Morphology
River sharks are very similar in overall morphology to
requiem sharkRequiem sharks refers to all members of the family Carcharhinidae: this includes migratory, live-bearing sharks of warm seas such as the tiger shark, the blue shark, the bull shark, and the milk shark. The name comes from the French word for shark, "requin". Family members have the usual...
s of the genus
CarcharhinusCarcharhinus is the type genus of the requiem shark family, Carcharhinidae.- Species :* Blacknose shark, Carcharhinus acronotus
* Silvertip shark, Carcharhinus albimarginatus
...
, but can be distinguished from them by the following characteristics:
- cusps of lower teeth protrude prominently when mouth is closed;
- the second dorsal fin
A dorsal fin is a fin located on the backs of some fish, whales, dolphins, and porpoises, as well as the ichthyosaurs. Depending on the species, an animal can have up to three of them. Its main purpose is to stabilize the animal against rolling and assist in sudden turns...
is 1/2 to 3/5 the height of the first dorsal finA dorsal fin is a fin located on the backs of some fish, whales, dolphins, and porpoises, as well as the ichthyosaurs. Depending on the species, an animal can have up to three of them. Its main purpose is to stabilize the animal against rolling and assist in sudden turns...
;
- the origin of the second dorsal fin is slightly anterior to the origin of the anal fin;
- precaudal pit is longitudinal rather than crescent-shaped.
Species
- Ganges shark
The Ganges shark, Glyphis gangeticus, is a rare species of fresh water shark that dwells in the Ganges River. It should not be confused with the Bull shark, which also inhabits the Ganges River and is sometimes referred to as the Ganges shark....
, Glyphis gangeticus (MüllerJohannes Peter Müller , was a German physiologist, comparative anatomist, and ichthyologist not only known for his discoveries but also for his ability to synthesize knowledge.-Life:Müller was born in Koblenz....
& HenleFriedrich Gustav Jakob Henle was a German physician, pathologist and anatomist. He is credited with the discovery of the loop of Henle in the kidney. His essay "On Miasma and Contagia" was an early argument for the germ theory of disease...
, 1839)
- New Guinea river shark
The New Guinea river shark, Glyphis garricki, formerly Glyphis sp. C, is a recently described shark of the family Carcharhinidae. Its length is thought to be up to 2 m.Reproduction is viviparous, with three to eight pups per litter....
, Glyphis garricki CompagnoLeonard J. V. Compagno is an international authority on shark taxonomy and the author of many scientific papers and books on the subject, best known of which is his 1984 catalogue of shark species produced for the Food and Agriculture Organization of the United Nations.-Career:*Ph.D, Stanford...
, White, & Last, 2008
- Speartooth shark
The speartooth shark, Glyphis glyphis, is a shark of the family Carcharhinidae, found in the tropical waters of the western Pacific Ocean between latitudes 5° N and 21° S. This little-known species has an uncertain occurrence in Malaysia, Papua New Guinea, and Queensland, Australia. The...
, Glyphis glyphis (MüllerJohannes Peter Müller , was a German physiologist, comparative anatomist, and ichthyologist not only known for his discoveries but also for his ability to synthesize knowledge.-Life:Müller was born in Koblenz....
& HenleFriedrich Gustav Jakob Henle was a German physician, pathologist and anatomist. He is credited with the discovery of the loop of Henle in the kidney. His essay "On Miasma and Contagia" was an early argument for the germ theory of disease...
, 1839)
- Irrawaddy River shark
The Irrawaddy river shark, Glyphis siamensis, is a shark of the family Carcharhinidae, found in the tropical waters of the eastern Indian Ocean off the coast of Burma.The only known specimen is from the Ayeyarwady River, near Yangon...
, Glyphis siamensis (SteindachnerFranz Steindachner was an Austrian zoologist.Being interested in natural history, Steindachner took up the study of fossil fishes on the recommendation of his friend Eduard Suess...
, 1896)
- Bizant river shark
The Bizant river shark, Glyphis sp. A, is a scientifically undescribed shark of the family Carcharhinidae, found in the tropical waters about Australia. Its length is thought to be up to 2 m, possibly 3.Reproduction is presumed to be viviparous....
, Glyphis sp. A, not yet described.
- Borneo river shark
The Borneo river shark, Glyphis sp. B, is a scientifically undescribed shark of the family Carcharhinidae. Its length is thought to be up to 2 m.Reproduction is presumed to be viviparous.-References:...
, Glyphis sp. B, not yet described.
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